As medicine requires an accurate knowledge of certain constituents of blood, it is desirable to improve various analytical tests to determine the content of various constituents of the blood, such as binding proteins and hormones. Various thyroid hormones are produced in the thyroid gland and are carried in the blood to the body cells where the hormones ultimately produce their well known metabolic effects. The hormones secreted by the thyroid gland include thyroxin, T4, and triiodothyronine, T3. The liver produces proteins such as thyroxin binding globulins (TBG) which are also important in regulating thyroid function.
Upon entering the blood, substantial amounts of T4 and T3 become bound to thyroxine binding proteins, (TBP), in a reversible manner. While the hormones are transported throughout the blood in mostly bound form, clinical studies have shown that it is the concentration of "free" thyroid hormones, e.g. FT4 or FT3 that determines the thyrometabolic status of an individual.
Because of the importance of these various substances, total T4, total T3, free T4, free T3, TBG and other thyroid hormone binding proteins, it is worthwhile to determine their content in the blood.
Various analytical techniques have been proposed. One technique for estimating TBP is an electrophoretic technique which is quite accurate but rather cumbersome for routine clinical medicine.
U.S. Pat. No. 3,451,777 DiGiulio teaches a method and apparatus for determining the thyroid hormone content of blood using a tube, open at the top and bottom, with a resin column therebetween for binding T3.
Nicoloff, et al., Obstetrics and Gynecology, Vol. 35, No. 2, February 1970, pages 191-198 teaches the use of a resin sponge technique for estimating TBG values. The method proposed is a modification of the T3 Resin Uptake Test of which U.S. Pat. No. 3,451,777 DiGiulio is an example.
A good summary of related radioimmunoassay (RIA) techniques is given in Clinical Chemistry, Vol. 19, No. 2, 1973, pp 145-174.
TBG may also be measured by RIA techniques.
An object of the present invention is to provide a simplified means of measuring binding protein content in blood.
A further object of this invention is to provide a rapid and simple procedure for measuring the TBP level in blood, which can be readily utilized by unskilled technicians in carrying out the method of the invention and in particular for measuring FT4. A further object of the invention is to provide a rapid and simple procedure for measuring antibody levels in blood.